Pumping unit



April 3, 1962 J. w. WINFREY PUMPING UNIT 2 Sheets-Sheet 1 Filed NOV. 24, 1959 INVENTOR.

INFREY,

ATTORNEY J. W. WINFREY PUMPING UNIT April 3, 1962 2 Sheets-Sheet 2 Filed Nov. 24, 1959 INVENTOR. JAMES W. WINFREY,

ATTORNEY.

FIG. 4.

United States Patent Ofihce 3,927,? tit Patented Apr. 3, 1. 1 62 3,027,771 PUMPING UNIT James W. Winfrey, Houston, Tex., assignor, by mesue assignments, to Jersey Production Research Company, Tulsa, 0kla., a corporation of Delaware Filed Nov. 24, 1959, Ser. No. 855,205 6 Claims. (Cl. 7437) The present invention concerns a dual sucker rod pumping unit.

In recent years, in an effort to reduce the cost of drilling and completing oil and gas wells, many wells have been completed in two producing horizons or zones and the production conducted to the surface through two parallel spaced-apart tubing strings.

In the case of dual oil wells requiring artificial lift for both producing zones, the pumping equipment many times limits the ability to produce the allowable of both zones and also the cost of the surface equipment may be a limiting factor in the economic feasibility of the dual completion.

To provide complete flexibility of operation, it has been a practice to set two completely independent beam pumping units, each having its own prime mover. This arrangement generally referred to as head-to-head pumping has the advantage of independent adjustment of speed, stroke length, counterweight, and pumping schedule; however, it has the disadvantages of high initial cost and difficulties encountered because of the close clearances between the horseheads and carrier bars.

It is an object of the present invention to provide in one pumping unit, driven by one prime mover, the flexibility of two independent units with a reduction in the cost of the initial installation and without, at the same time, encountering the close clearance problem.

In brief, the invention comprises apparatus for pumping both zones of a dually completed well comprising two spaced-apart polished rods extending from the Well, a frame, a first-crank having a counterweight connected thereto, a second crank having a counterweight connected thereto, means connected to said cranks for rotation thereof, a plurality of sheaves mounted on said frame, and cable means reaved about said sheaves interconnecting said cranks and polished rods in a manner such that said sucker rods reciprocate in said well upon rotation of the cranks.

The above object and other objects of the invention will be apparent from a more detailed description of the invention taken in conjunction with the drawing wherein:

FIG. 1 is an isometric view of one embodiment of the invention;

FIG. 2 is a schematic view illustrating the direction of movement of the cranks, sheaves and cables;

FIG. 3 is an isometric view of another embodiment of the invention; and

FIG. 4 is an enlarged isometric view of one portion of the apparatus of FIG. 3.

Referring to the drawings in greater detail, in FIG. 1 is shown a wellhead 1t? through which extends two tubing strings 11 and 12 to which are connected production conduits 13 and 14, respectively. A polished rod 15 extends into the upper end of tubing string 11 and a polished rod 16 extends into the upper end of tubing string 12. Positioned adjacent wellhead is a skid 20 on which is arranged a frame 21. An API twin crank pumping unit gear reducer 22 to which is connected :1 drive, not shown, is mounted on skid 20. Two cranks 23 and 24 having counterweights 25 and 26, respectively, are connected to and are driven by gear reducer 22. Cranks 23 and 24 are mounted out of phase. Instead of employing a walking beam, conventional Samson post, pitmans, and horsehead to convert the rotating motion of the crank wrist pin to the reciprocating motion needed to lift a string of sucker rods, 21 cable and pulley system supported by fixed frame 21 and skid 20 is employed. A cable 27 is reaved over sheaves 28 and 29 arranged on frame 21. One end of cable 27 con nects to crank 23 through a wrist pin 3% and extensible link 31. The other end of cable 27 wraps around a sheave or drum 32 which is supported on skid 2i and mounted for rotation on a countershaft 33. A cable 35 is reaved on sheaves 36 and 37 and interconnects crank 24 to a wrist pin, not seen, and extensible link 38 and a drum or sheave 39 also connected to countershaft 33 in a similar manner as sheave 32. Cable 27 wraps around drum 32 in one direction and cable 35 wraps around drum 39 in an opposite direction. A cable 41, one end of which is connected to polished rod 16 which supports a string of sucker rods and the other end of which is Wrapped around a drum or sheave 42, is reaved over pulleys 43 and 44. Similarly, a cable 45, one end of which is connected to polished rod 15 and the other end of which is wrapped around a drum or sheave 46, is reaved about sheaves 47 and 48. Cable 41 is wrapped around drum 42 on the same side or direction as cable 27 is wrapped around drum 32 and cable 45 is wrapped around drum 46 on the same side or direction as cable 35 is wrapped around drum 39. Drum 42 is releasably connected to countershaft 33 by a jaw-clutch 50 and similarly drum 46 releasably connects to countershaft 33 by means of a jaw-clutch, not seen.

The operation is clearly illustrated in FIG. 2. As reduction gear 22 rotates cranks 23 and 24, countershaft 33 is caused to oscillate. Drums 32 and 39 must be of the same diameter and cables 27 and 35 also must be of the same diameter. The diameter of drums 32 and 39 can be any convenient dimension.

A circumference approximately equal to twice the reduction gear crank length is desirable so that in each rotation of the cranks, countershaft 33 will oscillate 360. As countershaft 33 oscillates through rotation of reduction gear 22, cables 41 and 45 reciprocate in op posite directions and polished robs 15 and 16 also reciprocate in opposite directions. Frame 21 may be hinged as at 51 so that the portion of frame 21 upon which sheaves 44 and 48 are arranged can be folded back to permit access to the well of well servicing equipment. Sheaves 43, 47, 44, and 48 may be canted inward toward the centerline of the unit at the well end. The mount ing for these sheaves may be made adjustable so that the center-to-center distance on the pitch diameter of outboard grooves of sheaves 44 and 48 is the same as the center-to-center distance of the well polished rods. The rims of drums 42 and 45 may be made detachable so that the diameters of these sheaves or drums can be changed. Changing the diameters of drums 42 and 46 is a means for adjusting the sucker rods stroke lengths.

Extensible links 31 and 38 may be-springs, pneumatic cylinders, or hydraulic cylinders. Constant tension springs are applicable but are not essential. These links must be extensible because the sum of the distances from the upper end of the connecting links to sheaves 28 and 36 must remain constant for countershaft 33 to be a onepiece shaft. This is a necessary requirement for one well to be balanced against the other and for use of cable pitmans. Since the distance from wrist pin 30 to sheave 28 varies directly with the cosine and the crank angle, the rate of change of the length of link 31 varies throughout the rotation of the crank. Of course, the same is true for link 38 on the other side of the unit. Jawclutches 50 are provided to permit one well to be shutdown while the other continues to pump. Sufficient counterweight is provided on each crank to balance the well pumped on that side. Each counterweight is adjustable so that when one well is shut-down and the other well requires pumping, the counterweight of the shutdown well will be moved to dead-center of the crank so as not to overload the reduction gear.

An advantageous feature of the invention is that maximum torque load on the reduction gear from each of the two rod strings does not occur simultaneously. Therefore, the sum of the torque load from the two wells at any time is always less than the sum of the maximum torque load from the two wells. As an example, in the case of a pumping unit with a 6-foot stroke, that is, the radius of the crank is 3 feet, if the distance from the crankshaft center to the crown sheaves 28 or 36 is 10 feet, maximum torque load caused by each well will occur at approximately 72.2 crank angle at which time the crank is at 90 to the pitman. When one crank is at 72.2 the other crank will be at 252.2. In this position, the second cranks effective length is calculated as 2.54 feet. Thus, the torque on the reduction gear exerted by the crank at 252.2 is reduced in the ratio of 2.54:3. The maximum total torque on the reduction gear, assuming the two wells weigh the same, will be reduced in the ratio of 5.54:6, a reduction of 7.7 percent, when compared with pumping the two wells in phase. This is the same as increasing the torque capacity of the API gear box by 7.7/92.3 or 8.35 percent.

One other feature of this embodiment of the invention is that the center distance between the well-polished rods may be adjusted by adjusting the positions of crown sheaves 43 and 44, or 47 and 48. This distance may be made very close.

Another embodiment of the invention is illustrated in FIGS. 3 and 4. As seen in FIG. 3, a wellhead 10 has extending therefrom tubing strings 11 and 12 to which are connected production conduits 13 and 14, respectively. Also, polished rods 15 and 16 extend into tubing strings 11 and 12, respectively.

A skid 20 supports a frame 60 and an API twin-crank pumping unit gear reducer 22 to which is connected cranks 23 and 24, 180 out of phase. Crank 23 is provided with a counterweight 25 and crank 24 is provided with a counterweight 26. A cable 61 is reaved over sheaves 62 and 63 which are mounted on frame 60. One end of cable 61 connects to polished rod 16 and the other end of cable 61 connects to a detachable link 64 which in turn is connected to a wrist pin 65 connected to crank 23. Similarly, a cable 66 is reaved over sheaves 67 and 68 which are also arranged on frame 66. One end of cable 66 is connected to polished rod 15 and the other end of cable 66 connects to a detachable link 69 which connects to crank 24 by means of a wrist pin not seen. As in the previous embodiment and as more clearly seen in FIG. 4, the end of frame 60 adjacent sheaves 63 and 68 may be hinged as at 70 to permit the sheaves to be moved away from the well to permit access to the Well of well-servicing equipment.

The operation should be apparent. As reduction gear 22 rotates cranks 23 and 24, cables 61 and 66 reciprocate polished rods 15 and 16 in opposite directions.

In this embodiment, the countershaft and clutching mechanisms have been eliminated and only one pair of cables is required. Also, since the pitman cables 61 and 66 are independent of each other, links 64 need not be extensible; however, the links must be easily detachable because cables 61 and 66 must be disconnected from A wrist pins 65 and pulled out of the way when one of the dual wells is shut-down and the other requires pumping. In this arrangement, the stroke length of the well is adjustable by moving the wrist pin location in the crank in the conventional manner. Sheaves 62 and 6'7 are canted toward the center line of the supporting structure 60 so that the sheave grooves will be in line with the grooves of sheaves 63 and 66, respectively. Also, this embodiment will be less expensive than the previously described embodiment because the countershaft assembly and the four crown sheaves have been eliminated. On the other hand, the embodiment of FIGS. 1 and 2 will require less operating labor because the connecting links need not be disconnected to take oif the well but rather a simple clutch disengaging action is required. In both arrangements, the counterweight must be shifted to dead center when one well is disconnected.

Having fully described the elements, operation, and objects of my invention, 1 claim:

1. Apparatus for pumping separately dual Zones of a dually completed well through two separate tubing strings comprising two spaced-apart vertically reciprocal polished rods, one of said rods extending into one of said tubing strings and the other rod extending into the other tubing string, a frame, a first rotatable crank having a counterweight, a second rotatable crank having a counterweight, said first and second cranks being arranged out of phase, a plurality of sheaves mounted on said frame, cable means reaved about said sheaves and interconnecting said cranks and said polished rods in a manner such that rotation of said cranks reciprocates said polished rods in opposite directions, and means for rotating said cranks.

2. Apparatus as recited in claim 1 wherein the grooves of two of said sheaves are vertically aligned with said polished rods, and including hinge means arranged on said frame adapted to permit said two sheaves to be moved such that the grooves thereof are out of vertical alignment with said polished rods.

3. Apparatus for pumping separately two Zones of a dually completed well through two separate tubing strings comprising two spaced-apart vertically reciprocal polished rods, one of said rods extending into one of said tubing strings and the other rod extending into the other tubing string, a frame, a finst rotatable crank having a counterweight, a second rotatable crank having a counterweight, said first and second cranks being arranged 180 out of phase, a plurality of sheaves arranged on said frame, an oscillatable shaft, first, second, third and fourth drums mounted on said shaft, said second and third drum-s being releasably attached to said shaft, a first cable interconnecting said first crank and said first drum, a second cable interconnecting one of said polished rods and said second drum, a third cable interconnecting said other polished rod and said third drum, a fourth cable interconnecting said second crank and said fourth drum, said cables being arranged about said drums in a manner such that rotation of said cranks reciprocates said polished rods in opposite directions, and means adapted to rotate said cranks.

4. Apparatus as described in claim 3 wherein an extensible link interconnects said first cable and said first crank and said fourth cable and said second crank.

5. Apparatus for pumping separately two zones of a dually completed well through two separate tubing strings comprising two spaced-apart vertically reciprocal polished rods, one of said rods extending into one of said tubing strings and the other red extending into the other tubing string, a frame, a first rotatable crank having a counterweight, a second rotatable crank having a counterweight, said first and second cranks being arranged 180 out of phase, a plurality of sheaves arranged on said frame, a first cable arranged on said sheaves and interconnecting one of said polished rods and said first crank, a second cable arranged on said remaining sheaves interconnecting said other polished rod and said second crank, and a prime mover adapted to rotate said cranks whereby said polished rods are reciprocated in opposite directions.

6. Apparatus as recited in claim 5 wherein a detachable linkage interconnects said cables and said cranks.

References Cited in the file of this patent UNITED STATES PATENTS Bonham et a1 July 28, 1891 Heberling May 14, 1912 10 Page Aug. 12, 1913 Laughter June 2, 1925 

